U.S. patent application number 11/617449 was filed with the patent office on 2007-09-20 for prosthetic device and system and method for implanting prosthetic device.
This patent application is currently assigned to MAKO Surgical Corporation. Invention is credited to Rony Abovitz, Steven B. Brown, Binyamin Hajaj, Amit Mistry, Scott Nortman, Jason K. Otto.
Application Number | 20070219639 11/617449 |
Document ID | / |
Family ID | 38105416 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070219639 |
Kind Code |
A1 |
Otto; Jason K. ; et
al. |
September 20, 2007 |
PROSTHETIC DEVICE AND SYSTEM AND METHOD FOR IMPLANTING PROSTHETIC
DEVICE
Abstract
A prosthetic device includes one or more components configured
to be disposed in a joint. The component includes at least one
feature configured to provide information about the component. The
information can be used to determine or create the relationship
between the component and the joint and/or other components. This
relationship may be used to evaluate and/or modify the expected
performance of the prosthetic device and assist in determining the
optimal relationship between one or more components and a patient's
anatomy.
Inventors: |
Otto; Jason K.; (Plantation,
FL) ; Hajaj; Binyamin; (Plantation, FL) ;
Abovitz; Rony; (Hollywood, FL) ; Mistry; Amit;
(Plantation, FL) ; Nortman; Scott; (Sunrise,
FL) ; Brown; Steven B.; (Coral Springs, FL) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
MAKO Surgical Corporation
|
Family ID: |
38105416 |
Appl. No.: |
11/617449 |
Filed: |
December 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60782356 |
Mar 14, 2006 |
|
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|
Current U.S.
Class: |
623/20.19 ;
623/20.28; 623/914 |
Current CPC
Class: |
A61B 34/30 20160201;
A61F 2002/3895 20130101; A61F 2/38 20130101; A61B 90/96 20160201;
A61F 2/3859 20130101; A61F 2/3877 20130101; Y10S 623/914 20130101;
A61F 2002/4661 20130101; Y10S 623/908 20130101; A61F 2002/4662
20130101; A61F 2/389 20130101; A61F 2002/488 20130101; A61F 2/4657
20130101; A61F 2002/4658 20130101; A61B 34/70 20160201 |
Class at
Publication: |
623/20.19 ;
623/914; 623/20.28 |
International
Class: |
A61F 2/38 20060101
A61F002/38 |
Claims
1. A prosthetic device comprising: a component configured to be
disposed in a joint, wherein the component includes at least one
feature configured to provide information about the component.
2. The prosthetic device of claim 1, wherein the information
indicates at least one of a position, an orientation, a size, and
an identity of the component.
3. The prosthetic device of claim 1, wherein the information
relates to a relationship between the component and another
component disposed in the joint.
4. The prosthetic device of claim 1, wherein the information
relates to a rate of wear of the component.
5. The prosthetic device of claim 1, wherein the at least one
feature includes at least one of a sensor, a signal emitter, a
piezoelectric transducer, an optical etching, an optical marking, a
marker, a pattern, a landmark, an interface for an instrument, a
point, a line, an axis, a length, an arc center, a curve, a radius,
a plane, a surface, an articular surface, a virtual feature, a
correspondence point, an anatomic location, a soft tissue
insertion/attachment point, a divot, a cavity, a size, and an
ID.
6. The prosthetic device of claim 5, wherein the interface includes
at least one of a divot, a surface, and a cavity.
7. The prosthetic device of claim 1, wherein the at least one
feature is configured to provide the information about the
component when at least a portion of the component is covered with
tissue.
8. A collection of components for forming a prosthetic device
comprising: a first component configured to be disposed in a joint
and including a first feature; a second component configured to be
disposed in the joint and including a second feature; wherein the
first feature is configured to convey information about the first
component and the second feature is configured to convey
information about the second component.
9. The collection of components of claim 8, wherein the information
about the first component includes at least one of a position, an
orientation, a size, and an identity of the first component and the
information about the second component includes at least one of a
position, an orientation, a size, and an identity of the second
component.
10. The collection of components of claim 8, wherein at least one
of the information about the first component and the information
about the second component relates to a relationship between the
first component and the second component.
11. The collection of components of claim 8, wherein the
information about the first component relates to a rate of wear of
the first component.
12. The collection of components of claim 8, wherein the
information about the second component relates to a rate of wear of
the second component.
13. The collection of components of claim 8, wherein at least one
of the first feature and the second feature includes at least one
of a sensor, a signal emitter, a piezoelectric transducer, an
optical etching, an optical marking, a marker, a pattern, a
landmark, an interface for an instrument, a point, a line, an axis,
a length, an arc center, a curve, a radius, a plane, a surface, an
articular surface, a virtual feature, a correspondence point, an
anatomic location, a soft tissue insertion/attachment point, a
divot, a cavity, a size, and an ID.
14. The collection of components of claim 13, wherein the interface
includes at least one of a divot, a surface, and a cavity.
15. The collection of components of claim 8, wherein the first
feature is configured to provide the information about the first
component when at least a portion of the first component is covered
with tissue.
16. The collection of components of claim 8, wherein the second
feature is configured to provide the information about the second
component when at least a portion of the second component is
covered with tissue.
17. A surgical method comprising the steps of: acquiring
information about a first implant disposed in a joint; acquiring
information about a second implant disposed in the joint; and
determining a relationship between the first implant and the second
implant based at least in part on the information acquired about
the first implant and the information acquired about the second
implant.
18. The surgical method of claim 17, further comprising the step
of: comparing the determined relationship to a desired
relationship.
19. The surgical method of claim 18, further comprising the step
of: adjusting at least one of the first implant and the second
implant to achieve the desired relationship.
20. The surgical method of claim 17, wherein the information about
the first implant includes at least one of a position, an
orientation, a size, and an identity of the first implant and the
information acquired about the second implant includes at least one
of a position, an orientation, a size, and an identity of the
second implant.
21. The surgical method of claim 17, further comprising the step
of: determining a rate of wear of the first implant based on the
information acquired about the first implant.
22. The surgical method of claim 17, further comprising the step
of: determining a rate of wear of the second implant based on the
information acquired about the second implant.
23. The surgical method of claim 17, further comprising the step
of: applying a force to the joint when the information about the
first implant and the information about the second implant are
acquired.
24. The surgical method of claim 17, further comprising the step
of: determining a relative position of the first implant and the
second implant based at least in part on the information acquired
about the first and second implants.
25. The surgical method of claim 17, further comprising the step
of: determining a condition of soft tissue in the joint based at
least in part on the information acquired about the first and
second implants.
26. The surgical method of claim 17, wherein the step of acquiring
information about the first implant includes at least one of
contacting at least a portion of the first implant with an
instrument and scanning at least a portion of the first implant
with a detection device.
27. The surgical method of claim 17, wherein the step of acquiring
information about the second implant includes at least one of
contacting at least a portion of the second implant with an
instrument and scanning at least a portion of the second implant
with a detection device.
28. The surgical method of claim 17, wherein the information about
the first implant is acquired when at least a portion of the first
implant is covered with tissue.
29. The surgical method of claim 17, wherein the information about
the second implant is acquired when at least a portion of the
second implant is covered with tissue.
30. The surgical method of claim 17, wherein the first implant
includes a first feature configured to provide the information
about the first implant and the second implant includes a second
feature configured to provide the information about the second
implant.
31. The surgical method of claim 30, wherein at least one of the
first feature and the second feature includes at least one of a
sensor, a signal emitter, a piezoelectric transducer, an optical
etching, an optical marking, a marker, a pattern, a landmark, an
interface for an instrument, a point, a line, an axis, a length, an
arc center, a curve, a radius, a plane, a surface, an articular
surface, a virtual feature, a correspondence point, an anatomic
location, a soft tissue insertion/attachment point, a divot, a
cavity, a size, and an ID.
32. A surgical method comprising the steps of: acquiring
information about a first implant disposed in a joint; and planning
placement in the joint of a second implant based at least in part
on the information acquired about the first implant and a desired
relationship between the first implant and the second implant.
33. The surgical method of claim 32, wherein the information about
the first implant includes at least one of a position, an
orientation, a size, and an identity of the first implant.
34. The surgical method of claim 32, wherein the step of acquiring
information includes at least one of contacting at least a portion
of the first implant with an instrument and scanning at least a
portion of the first implant with a detection device.
35. The surgical method of claim 32, further comprising the step
of: determining a rate of wear of the first implant based on the
information acquired about the first implant.
36. The surgical method of claim 32, wherein the information about
the first implant is acquired when at least a portion of the first
implant is covered with tissue.
37. The surgical method of claim 32, wherein the desired
relationship between the first and second implants relates to at
least one of a position and an orientation of the first and second
implants.
38. The surgical method of claim 32, further comprising the steps
of: positioning the second implant in the joint; acquiring
information about the second implant; and determining a
relationship between the first implant and the second implant based
at least in part on the information acquired about the first
implant and the information acquired about the second implant.
39. The surgical method of claim 38, further comprising the step
of: comparing the determined relationship to the desired
relationship.
40. The surgical method of claim 39, further comprising the step
of: adjusting at least one of the first implant and the second
implant to achieve the desired relationship.
41. The surgical method of claim 38, wherein the information about
the second implant includes at least one of a position, an
orientation, a size, and an identity of the second implant.
42. The surgical method of claim 32, wherein the first implant
includes a first feature configured to provide the information
about the first implant and the second implant includes a second
feature configured to provide information about the second
implant.
43. The surgical method of claim 42, wherein at least one of the
first feature and the second feature includes at least one of a
sensor, a signal emitter, a piezoelectric transducer, an optical
etching, an optical marking, a marker, a pattern, a landmark, an
interface for an instrument, a point, a line, an axis, a length, an
arc center, a curve, a radius, a plane, a surface, an articular
surface, a virtual feature, a correspondence point, an anatomic
location, a soft tissue insertion/attachment point, a divot, a
cavity, a size, and an ID.
44. A system for implanting a prosthetic device comprising: a first
component configured to be disposed in a joint and including a
first feature; a second component configured to be disposed in the
joint and including a second feature; and a computer programmed to
determine a relationship between the first component and the second
component based at least in part on the first feature and the
second feature.
45. The system of claim 44, wherein at least one of the first
feature and the second feature includes at least one of a sensor, a
signal emitter, a piezoelectric transducer, an optical etching, an
optical marking, a marker, a pattern, a landmark, and an interface
for an instrument, a point, a line, an axis, a length, an arc
center, a curve, a radius, a plane, a surface, an articular
surface, a virtual feature, a correspondence point, an anatomic
location, a soft tissue insertion/attachment point, a divot, a
cavity, a size, and an ID.
46. The system of claim 44, wherein the relationship between the
first component and the second component relates to at least one of
a position and an orientation of the first and second
components.
47. The system of claim 44, wherein the computer is programmed to
compare the relationship between the first component and the second
component to a desired relationship.
48. The system of claim 47, wherein the desired relationship
relates to at least one of a position and an orientation of the
first and second components.
49. The system of claim 47, wherein the computer is programmed to
determine the desired relationship based on at least one of an
image dataset, an imageless dataset, an equation, a tolerance, and
a geometric model.
50. The system of claim 44, wherein the computer is programmed to
determine at least one of a rate of wear and a life of the first
component based at least in part on the first feature.
51. The system of claim 44, wherein the computer is programmed to
determine at least one of a rate of wear and a life of the second
component based at least in part on the second feature.
52. A system for implanting a prosthetic device comprising: a first
component configured to be disposed in a joint including a first
feature providing first information; a second component configured
to be disposed in the joint including a second feature providing
second information; and a computer programmed: to create at least
one relationship between the first component and the second
component based at least in part on the first feature and the
second feature, and to evaluate the relationship based on at least
one condition.
53. The system of claim 52, wherein at least one of the first
component and the second component includes at least one of an
implant, a trial implant and a bone.
54. The system of claim 53, wherein at least one of the first
component and the second component includes at least one of a
femoral component, a patello-femoral component, a tibial component,
a femur, a tibia, and a patella.
55. The system of claim 52, wherein at least one of the first
feature and the second feature includes at least one of a sensor, a
signal emitter, a piezoelectric transducer, an optical etching, an
optical marking, a marker, a pattern, a landmark, an interface for
an instrument, a point, a line, an axis, a length, an arc center, a
curve, a radius, a plane, a surface, an articular surface, a
virtual feature, a correspondence point, an anatomic location, a
soft tissue insertion/attachment point, a divot, a cavity, a size
and an ID.
56. The system of claim 52, wherein at least one of the first
information and the second information indicates at least one of a
position, an orientation, a size, an identity, and a performance
characteristic of the corresponding one of the first component and
the second component.
57. The system of claim 52, wherein the at least one relationship
is at least one of a distance, a distance limit, an angle, an angle
limit, a tangent, an orientation, a moment arm length, a collinear
orientation, a concentric orientation, a coplanar orientation and a
potential implant position.
58. The system of claim 52, wherein the condition is at least one
performance characteristic.
59. The system of claim 58, wherein the performance characteristic
is at least one of wear, stress, kinematics, kinetics, fixation
strength, ligament balance, anatomic fit and longevity.
60. The system of claim 53, wherein the computer is further
programmed to propose a modification of the at least one
relationship between the first component and the second component
based on the at least one condition.
61. The system of claim 53, wherein the computer is further
programmed to determine an optimal relationship between the first
component and the second component, wherein the first component is
a pre-existing implant in a suboptimal position.
62. A system for implanting a prosthetic device comprising: a
plurality of components configured to be disposed in a joint,
wherein each component includes at least one feature providing
information; and a computer programmed: to create at least one
relationship between the plurality of components based at least in
part on the feature of the plurality of components, and to evaluate
the relationship based on at least one condition.
63. A surgical method comprising the steps of: acquiring a first
feature of a first component configured to be disposed in a joint;
acquiring a second feature of a second component configured to be
disposed in the joint; determining a relationship between the first
feature and the second feature; and evaluating the relationship
based on at least one condition.
64. The surgical method of claim 63, wherein at least one of the
first component and the second component includes at least one of
an implant and a trial implant.
65. The surgical method of claim 64, wherein at least one of the
first component and the second component includes at least one of a
femoral component, a patello-femoral component, and a tibial
component.
66. The surgical method of claim 63, wherein at least one of the
first feature and the second feature includes at least one of a
sensor, a signal emitter, a piezoelectric transducer, an optical
etching, an optical marking, a marker, a pattern, a landmark, and
an interface for an instrument.
67. The surgical method of claim 63, wherein at least one of the
first feature and the second feature indicates at least one of a
position, an orientation, a size, an identity, and a performance
characteristic of the corresponding one of the first component and
the second component.
68. The surgical method of claim 63, wherein the at least one
relationship is at least one of a distance, a distance limit, an
angle, an angle limit, a tangent, an orientation, a moment arm
length, a collinear orientation, a concentric orientation, a
coplanar orientation and a potential implant position.
69. The surgical method of claim 63, wherein the condition is at
least one performance characteristic.
70. The surgical method of claim 69, wherein the performance
characteristic is at least one of wear, stress, kinematics,
kinetics, fixation strength, ligament balance, anatomic fit and
longevity.
71. The surgical method of claim 63, further comprising proposing a
modification of the at least one relationship between the first
component and the second component based on the at least one
condition.
72. The surgical method of claim 63, wherein the first feature and
second feature are acquired by at least one of laser probing,
ultrasound probing, physical instrument probing, RFID detection,
and CAD modeling.
73. A surgical method comprising the steps of: acquiring a first
feature of a first component of a joint; acquiring a second feature
of a second component of the joint; relating the first feature to
the second feature based on a relationship; and modifying the
relationship based on a performance characteristic.
74. A surgical method comprising the steps of: acquiring a feature
of a plurality of components configured to be disposed in a joint;
creating a relationship between the features of the plurality of
components; and evaluating the relationship based on at least one
condition.
75. The surgical method of claim 74, wherein the acquiring step
includes acquiring a feature of at least components and the
creating step includes creating a relationship between the features
of the at least three components.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to orthopedic joint replacement and,
more particularly, to a prosthetic device for use in orthopedic
joint replacement and a system and method for implanting the
same.
[0003] 2. Description of Related Art
[0004] As shown in FIG. 1, conventional total knee arthroplasty
(TKA) systems typically include a femoral component 500 that is
implanted on the distal end of the femur and replaces the bearing
surfaces of the femur, a tibial component 502 that is implanted on
the proximal end of the tibia and replaces the bearing surfaces of
the tibia, and a patellar component (not shown) that replaces the
undersurface of the patella. The tibial component 502 typically
includes a tibial baseplate (or tray) 502a that is affixed to the
bone and a tibial insert 502b that is disposed on the tibial
baseplate 502a and forms the bearing surfaces of the tibial
component 502. In operation, the bearing surfaces of the femoral
component 500 articulate against the bearing surfaces of the tibial
component 502 as the knee joint moves through a range of
motion.
[0005] One disadvantage of conventional TKA systems is that they
limit the ability to perform surgery through MIS incisions. For
example, the femoral component 500 and the tibial component 502 are
too large to fit through minimally invasive surgery (MIS)
incisions, which are considerably smaller than incisions used in
traditional surgical approaches. Another disadvantage is that the
femoral component 500 and the tibial component 502 have fixed
geometry and are available in a limited range of sizes. As a
result, the surgeon may be unable to achieve an optimal fit for
each patient and may be forced to remove healthy as well as
diseased bone to accommodate the implant. Thus, conventional TKA
systems lack the flexibility to enable the surgeon to select
implant components that are customized to accommodate a patient's
unique anatomy and/or disease state.
[0006] In an effort to overcome these disadvantages, modular knee
prostheses comprising multiple components that are inserted
separately and assembled within the surgical site have been
developed. One example of a modular system is described in U.S.
patent application Ser. No. 11/312,741, filed Dec. 30, 2005, which
is hereby incorporated by reference herein in its entirety.
Computer aided design can be used to create a variety of
components, certain of which are intended to provide a more
customized fit based on a patient's particular circumstances and
characteristics (e.g., anatomy and/or disease state). Such modular
systems offer increased flexibility to the surgeon and may result
in an improved fit. Such systems present a challenge, however, as
they generally require a high degree of insertion accuracy to
properly place the components relative to one another. For example,
whereas the femoral component 500 of a conventional TKA system
comprises a solid part having a fixed geometry (as shown in FIG.
1), a modular system may be constructed of individual modular
components that are each separately implanted in the joint. Thus,
the geometry of a modular system is variable depending on the
surgeon's placement of the separate modular components relative to
one another. To ensure that a proper geometric relationship (e.g.,
distance, orientation, alignment, etc.) is established among all
modular components, each modular component must be inserted (or
positioned) in the joint with a high degree of accuracy. Achieving
the requisite accuracy requires significant surgical skill as well
as specialized instruments and technology. Because surgeons have
different skill levels and experience, operative results among
patients may not be sufficiently predictable and/or repeatable. As
a result, modular implant performance and longevity may vary among
patients.
[0007] Another disadvantage of both conventional and modular knee
implants is that monitoring implant wear and relative position over
time in a non-invasive manner is difficult. For example, although
installed implants may be imaged using X-ray or other imaging
technologies, such images do not provide sufficient clarity and/or
detail to enable precise tracking of implant wear and relative
position. As a result, surgeons are often unable to predict
precisely when an implant will need to be replaced or to determine
the condition of soft tissue in the joint in a non-invasive
manner.
[0008] In view of the foregoing, a need exists for techniques and
implants that enable improved insertion accuracy and relative
placement of implant components and non-invasive monitoring of
implant wear and relative position.
SUMMARY OF THE INVENTION
[0009] According to an aspect of the present invention, a
prosthetic device is provided. The prosthetic device includes a
component configured to be disposed in a joint. The component
includes at least one feature configured to provide information
about the component.
[0010] According to another aspect of the present invention, a
collection of components for forming a prosthetic device is
provided. The collection of components includes a first component
configured to be disposed in a joint and a second component
configured to be disposed in the joint. The first component
includes a first feature configured to convey information about the
first component, and the second component includes a second feature
configured to convey information about the second component.
[0011] According to yet another aspect of the present invention, a
surgical method is provided. The surgical method includes the steps
of acquiring information about a first implant disposed in a joint;
acquiring information about a second implant disposed in the joint;
and determining a relationship between the first implant and the
second implant based at least in part on the information acquired
about the first implant and the information acquired about the
second implant.
[0012] According to yet another aspect of the present invention, a
surgical method is provided. The surgical method includes the steps
of acquiring information about a first implant disposed in a joint
and planning placement in the joint of a second implant based at
least in part on the information acquired about the first implant
and a desired relationship between the first implant and the second
implant.
[0013] According to yet another aspect of the present invention, a
system for implanting a prosthetic device is provided. The system
includes a first component configured to be disposed in a joint and
a second component configured to be disposed in the joint. The
first component includes a first feature, and the second component
includes a second feature. The system also includes a computer
programmed to determine a relationship between the first component
and the second component based at least in part on the first
feature and the second feature.
[0014] According to still another aspect of the present invention,
a system for implanting a prosthetic device is provided. The system
includes a first component configured to be disposed in a joint
having a first feature. In addition, the system includes a second
component configured to be disposed in a joint including a second
feature. The system also includes a computer programmed to create
at least one relationship between the first component and the
second component based at least in part on the first feature and
the second feature. The computer is also programmed to evaluate the
relationship based on at least one condition.
[0015] According to still another aspect of the present invention,
a system for implanting a prosthetic device is provided. The system
includes a plurality of components configured to be disposed in a
joint. Each component includes at least one feature providing
information. The system also includes a computer programmed to
create at least one relationship between the plurality of
components based at least in part on the feature of the plurality
of components, and to evaluate the relationship based on at least
one condition.
[0016] According to still another aspect of the present invention,
a surgical method is provided. The surgical method includes the
steps of acquiring a first feature of a first component configured
to be disposed in a joint, acquiring a second feature of a second
component configured to be disposed in the joint, determining a
relationship between the first feature and the second feature; and
evaluating the relationship based on at least one condition.
[0017] According to still another aspect of the present invention,
a surgical method is provided. The surgical method includes the
steps of acquiring a first feature of a first component of a joint,
acquiring a second feature of a second component of the joint,
relating the first feature to the second feature based on a
relationship, and modifying the relationship based on a performance
characteristic.
[0018] According to still another aspect of the present invention,
a surgical method is provided. The surgical method includes the
steps of acquiring a feature of a plurality of components
configured to be disposed in a joint, creating a relationship
between the features of the plurality of components, and evaluating
the relationship based on at least one condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
principles of the invention.
[0020] FIG. 1 is a perspective view of a conventional total knee
arthroplasty system.
[0021] FIG. 2 is a perspective view of an embodiment of a
prosthetic device according to the present invention.
[0022] FIG. 3 is a perspective view of the prosthetic device of
FIG. 2 implanted on a femur and a tibia of a patient.
[0023] FIG. 4 is a perspective view of an embodiment of an
instrument according to the present invention.
[0024] FIG. 5 is a plan view of an embodiment of an interface
according to the present invention.
[0025] FIG. 6 is a perspective view of an embodiment of an
instrument according to the present invention.
[0026] FIG. 7 is a cross sectional view of an embodiment of an
interface according to the present invention.
[0027] FIG. 8 is a perspective view of an embodiment of a
prosthetic device and a patient's anatomy according to the present
invention.
[0028] FIGS. 9(a)-9(c) are perspective views of an embodiment of a
prosthetic device according to the present invention and a plan
view of a femur of a patient.
[0029] FIGS. 10(a)-10(d) are perspective and plan views of an
embodiment of a prosthetic device according to the present
invention.
[0030] FIGS. 11(a)-11(b) are perspective views of an embodiment of
a prosthetic device according to the present invention.
[0031] FIGS. 12(a)-12(c) are plan views of a bone of a patient.
[0032] FIGS. 13(a)-13(b) are plan views of an embodiment of a
prosthetic device according to the present invention implanted into
the bone of a patient.
[0033] FIG. 14 is a plan view of an embodiment of two prosthetic
device components according to the present invention.
[0034] FIG. 15 is a plan view of an embodiment of two prosthetic
device components according to the present invention.
[0035] FIG. 16 is a perspective view of an embodiment of a
prosthetic device simulation according to the present
invention.
[0036] FIG. 17 is a perspective view of an embodiment of two
prosthetic device components according to the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0037] Presently preferred embodiments of the invention are
illustrated in the drawings. An effort has been made to use the
same or like reference numbers throughout the drawings to refer to
the same or like parts.
[0038] FIG. 2 shows an embodiment of a prosthetic device 5
according to the present invention. In this embodiment, the
prosthetic device 5 is a modular total knee implant. The prosthetic
device 5, however, is not limited to knee implants. The prosthetic
device 5 may be any orthopedic joint implant, such as, for example,
a total knee implant; a unicondylar knee implant; a modular knee
implant; implants for other joints including hip, shoulder, elbow,
wrist, ankle, and spine; and/or any other orthopedic and/or
musculoskeletal implant, including implants of conventional
materials and more exotic implants, such as orthobiologics, drug
delivery implants, and cell delivery implants. In the alternative
the prosthetic device may be a trial of an implant. In one
embodiment, the implant is a modular knee implant as described in
U.S. patent application Ser. No. 11/312,741, filed Dec. 30, 2005,
which is hereby incorporated by reference herein in its
entirety.
[0039] The prosthetic device 5 of FIG. 2 includes a femoral portion
and a tibial portion formed from a collection of modular
components. The femoral portion includes a first component 10, a
second component 20, and a third component 30. The tibial portion
includes a fourth component 40 and a fifth component 50. Each
component of the prosthetic device 5 preferably includes at least
one feature configured to provide information about the
component.
[0040] As shown in FIG. 3, the first component 10 of the femoral
portion of the prosthetic device 5 is a femoral component
configured to be disposed on a medial or lateral condyle of a femur
F of a knee joint. The third component 30 is configured to be
disposed on the opposite condyle of the femur F and may be similar
to or different from the first component 10. In this embodiment,
the third component is substantially similar to the first component
10. The second component 20 is a patello-femoral (PF) component
configured to be disposed between the first and third components 10
and 30 on the PF joint of the femur F.
[0041] The tibial portion of the prosthetic device 5 includes the
fourth and fifth components 40 and 50. As shown in FIG. 3, the
fourth component 40 is a tibial component configured to be disposed
on a medial or lateral tibial plateau of a tibia T of the knee
joint. The fourth component 40 includes a baseplate (or tray) 40a
that is fixed to the tibia T and an insert 40b that is disposed on
the baseplate 40a. The fifth component 50 is configured to be
disposed on the opposite plateau of the tibia T and may be similar
to or different from the fourth component 40. In this embodiment,
the fifth component 50 is similar to the fourth component 40 and
includes a baseplate 50a that is fixed to the tibia T and an insert
50b that is disposed on the baseplate 50a. The prosthetic device 5
may also include a patellar component (not shown).
[0042] The components of the prosthetic device 5 may be made of any
material or combination of materials suitable for use in an
orthopedic implant. Suitable materials include, for example,
biocompatible metals (e.g., a cobalt-chromium alloy, a titanium
alloy, or stainless steel); ceramics (e.g., an alumina or
zirconia-based ceramic); high performance polymers (e.g.,
ultra-high molecular weight polyethylene); and/or a polymer
composite as described in U.S. patent application Ser. No.
10/914,615, U.S. Patent Application No. 11/140,775, and/or
International Application No. PCT/US2005/028234 (International Pub.
No. WO 2006/020619), each of which is hereby incorporated by
reference herein in its entirety. The prosthetic device 5 may be
attached to the femur F and the tibia T using any known fixation
method, such as, for example, mechanical hardware (e.g., screws) or
cement. Fixation may also be accomplished via bone in-growth. To
promote bone in-growth, the prosthetic device 5 may be coated with
hydroxyapatite (HA), have a porous texture (e.g., beads, etc.),
include one or more surfaces made from a porous metal (e.g.,
TRABECULAR METAL.TM. currently produced by Zimmer, Inc.), and/or
include one or more surfaces having a cellular engineered structure
(e.g., TRABECULITE.TM. currently produced by Tecomet).
[0043] The components of the prosthetic device 5 preferably each
include at least one feature configured to provide information
about the component. For purposes of explanation, a preferred
embodiment is shown in FIG. 3. In this embodiment, the first
component 10 includes a first feature 70a, the second component 20
includes a second feature 70b, the third component 30 includes a
third feature 70c, the fourth component 40 includes a fourth
feature 70d, and the fifth component 50 includes a fifth feature
70e.
[0044] The information provided by the feature may include, for
example, a position, an orientation, a size, an identity (e.g.,
part number), and/or any other useful information regarding the
component. For example, in operation, the feature can function as a
reference point or datum for the component (e.g., a shape, curve,
point, axis, etc.). Thus, the feature (in combination with a
detection device and a computing device) may be used as a basis for
calculating or determining a position and/or an orientation of the
component.
[0045] The feature may be integrated with the component in any
known manner. For example, the feature may be embedded in the
component, affixed to the component (e.g., using adhesive), formed
on a surface of the component (e.g., by etching, cutting, marking,
etc.), and/or formed integrally with the component. The feature can
take any of a variety of fomms, some of which are described
below.
[0046] The feature can be configured to be detectable (or readable)
by a detection device (or detection system) using any suitable
detection method. For example, the feature may be detected using
optical, electromagnetic, radio, and/or acoustic methods, as are
well known. As further examples, the feature may be detected using
a laser scanner or infrared camera. As yet additional examples, the
feature may be detected using a trackable probe or instrument in
combination with an infrared camera or a mechanical arm with joint
encoders. In a preferred embodiment, the detection device can read
the feature after the prosthetic device 5 has been implanted in the
patient and the joint has healed. Thus, for such an embodiment, an
incision is not required to read the feature and information can be
obtained from the feature in a non-invasive manner. For example,
during a follow up visit, the surgeon can obtain information about
a recently implanted prosthetic device and determine whether the
position and/or orientation of the modular components of the
prosthetic device are acceptable.
[0047] Some specific features and detection devices will now be
described. The invention is not intended to be limited to the
specific features described, nor is it intended to be limited to
the described combinations of features and detection devices.
[0048] The feature may include, for example, an optical
characteristic, such as an optical etching (e.g., a laser etching),
an optical marking (e.g., a bar code, a checkerboard pattern, or a
grid or array of dots), and/or a marker (e.g., a passive infrared
marker) that can be formed or disposed on a surface of the
component. Such a feature could be detected, for example, with a
detection device including a laser scanner or infrared camera.
[0049] As another example, the feature can include a pattern
disposed on a surface of the component. The pattern may include,
for example, textures, grooves, etchings, and the like. Such a
feature could be detected, for example, with a detection device
that includes a trackable probe that can be slid over the pattern
and an infrared camera that can detect the probe.
[0050] As another example, the feature can include a landmark or
surface characteristic. The landmark or surface characteristic may
be an integral or intrinsic part of the component that is
sufficiently defined and identifiable to function as a recognizable
marker (e.g., an articular surface, outlines of anatomical
structure, shapes, colors, etc.).
[0051] As yet another example, the feature can be an interface on
the component that is configured to interact with an instrument.
For example, the interface could receive at least a portion of the
instrument. The detection device could determine the pose of the
instrument engaged with the interface, and the computing device
could determine a location of the feature on the component based on
the pose of the instrument. The computing device can determine the
position and orientation of the component by determining the
location of multiple features and knowing a geometric relationship
between the features and the component.
[0052] The instrument may be, for example, an instrument 49 having
a probe 150 and an instrument tracker S5 as shown in FIG. 4 and
described in a U.S. patent application Ser. No. 11/357,197 titled
"Haptic Guidance System and Method," filed Feb. 21, 2006, and
hereby incorporated by reference herein in its entirety. The
instrument tracker S5 can include an array of markers (e.g.,
reflective spheres) detectable by a detection device (including,
e.g., an infrared camera) and having a unique geometric arrangement
and a known geometric relationship to the probe 150. The known
geometric relationship may be, for example, a predefined geometric
relationship between the array of markers and an endpoint and an
axis of the probe 150. Knowing the position and orientation (i.e.,
pose) of the tracker S5 and the geometric relationship between the
tracker S5 and the probe 150, a computing device can calculate or
determine the pose of the probe 150. In one embodiment, the
instrument includes a probe disposed on a mechanical tracking arm
as described in U.S. Pat. Nos. 6,033,415 and/or 6,322,567, each of
which is hereby incorporated by reference herein in its entirety.
In another embodiment, the instrument includes a haptic device 300
having a robotic arm 330 with a tool 350 as shown in FIG. 6 and
described in the U.S. patent application Ser. No. 11/357,197 titled
"Haptic Guidance System and Method," filed Feb. 21, 2006. The
robotic arm 330 includes joint encoders to enable a computing
device to determine a pose of the tool 350.
[0053] The interface can be configured to receive at least a
portion of the instrument. For example, as shown in FIG. 5, the
interface may include one or more divots 80 disposed on a surface
of the component and into which the user can insert a tip of the
instrument. The detection device can then acquire pose data for the
instrument, and the computing device can determine a location of
the divot by determining a location of the tip of the instrument.
Determining the location of three divots enables the computing
device to define a plane, which defines a position and orientation
of the feature. Knowing the position and orientation of the feature
and a geometric relationship between the feature and the component,
enables the computing device to determine the position and
orientation of the component. In this manner, the feature is
configured to provide information about the component. Alternately
or in addition to a divot, the interface may include one or more
surfaces (e.g., flat or contoured) on which a similarly shaped
probe (e.g., a probe having a flat or contoured tip) or trackable
mechanical jig may be disposed.
[0054] In one embodiment, the interface includes a cavity 82 (shown
in FIG. 7) into which a tip of the instrument may be inserted. The
cavity 82 may be, for example, a cylindrical cavity. When the
instrument is inserted in the cavity, an axis of the feature may be
determined. If the instrument is prevented from rotating in the
cavity, a third constraint is established so that the computing
device can calculate the position and orientation of the feature
and ultimately of the component. The instrument may be prevented
from rotating in any known manner. For example, at least a portion
of the cavity 82 may have a shape (e.g., a triangular shape, a
rectangular shape, etc.) that is keyed to a shape of at least a
portion of the instrument shaft so that the instrument is locked in
place when inserted into the cavity.
[0055] As yet another example, the feature may be a structure that
emits one or more signals that provide information. The feature
may, for example, emit a directional signal having a known
orientation relative to the component. Such a directional signal
allows for determining the location and/or orientation of the
component. A structure that could be used to provide such a
directional signal includes, for example, a transmitter positioned
on the edge of the implant. A detection device that could be used
to detect the directional signal includes, for example, a receiver
capable of triangulating and identifying a position. As another
example, the signal emitting structure may include at least one
sensor. The sensor may be, for example, a smart label such as a
passive radio frequency identification (RFID) tag. The RFID tag is
affixed to the surface of the component and/or embedded in the
component and is detectable by an RFID reader that emits radio
waves. As a user scans the component with the RFID reader, the
radio waves power the RFID tag, which then communicates with the
RFID reader. For example, a RFID reader may consist of two readers
at a known distance apart. A component may have three or four RFID
tags embedded in the component at known relative positions. The
readers send out a signal to excite the component tag and the
readers measure the time it takes for the signal to return. Each
reader is then able to compute the location of the component tag.
This is repeated sequentially for all tags in the component, all
within a fraction of a second. Once the location of all the tags in
the component are known, the pose of the implant is known. One
advantage of using a signal emitting structure is that the
detection device can obtain information from the structure even
when the prosthetic device 5 is not visible or exposed (e.g., when
the prosthetic device 5 is covered with tissue such as muscle and
skin). As a result, the signal emitting structure can provide
information about the component after the component has been
implanted and the patient's joint has healed. Thus, the component
can be monitored in a non-invasive manner at any time during the
life of the component.
[0056] As yet another example, the feature may include one or more
piezoelectric transducers embedded in the component. A
piezoelectric measuring system then can be used to measure
piezoelectric voltages generated in response to deflections of the
component. In the case of a joint having tibial and femoral
components, a particular stress and deflection pattern exists in
the tibial component due to forces applied by the femoral component
during normal joint operation. This deflection pattern will
correspond to a voltage pattern generated as a result of movement
of the piezoelectric transducers caused by the forces applied by
the femoral component. For a new tibial component, this voltage
pattern may be characterized as a "no wear" voltage pattern and can
be predicted and/or experimentally measured. Over time, as the
tibial component experiences wear, the deflection pattern of the
tibial component will change. This wear may be manifested, for
example, as a reduction in thickness and/or material properties of
the tibial component. As the deflection pattern changes, the
corresponding voltage pattern generated by the piezoelectric
transducers will change. Differences in the voltage pattern over
time can be detected and used to quantify wear of the tibial
component.
[0057] The ability to communicate information from the component
via the feature and the detection device provides a wide variety of
capabilities. For example, if the feature provides information to
the detection device regarding the position and/or orientation of
the feature, a computing device can calculate or determine the
position and/or orientation of the component based on that
information and a known geometric relationship between the feature
and the component.
[0058] The ability to determine the position of the component makes
it possible to determine the positioning of the component relative
to another component and/or relative to a plurality of other
components. In an instance where the components are, for example,
all parts of a prosthetic device configured to be disposed or
implanted in a joint, the present invention can provide an improved
ability to position those components relative to one another. In
the instance where at least one of the components is the patient's
bone disposed in the joint (e.g., femur, tibia, or patella), the
present invention can provide an improved ability to position the
component of the prosthetic device relative to the bone component.
In such an instance, the feature on the bone component may be, for
example, its shape, contour, correspondence point(s), and/or a
virtual feature from a model of the bone.
[0059] The positioning can be achieved in a variety of ways. For
example, when two or more components each include a feature, the
computing device can calculate or determine a desired position and
orientation of the components relative to one another (geometric
relationship(s)). During a surgical procedure, the computing device
(in combination with the detection device), can determine the
actual geometric relationship(s) of the components and then compare
the actual relationship(s) of the components to the desired
geometric relationship(s). If the actual relationships deviate from
the desired relationships, one or more of the components can be
repositioned or adjusted during the surgical procedure to achieve
the desired relationships.
[0060] The computing device (or computer) may be any suitable
computer, such as, for example, a computer aided surgery (CAS) or
surgical navigation system. In a preferred embodiment, the
computing device is a haptic guidance system as described in a U.S.
patent application Ser. No. 11/357,197 titled "Haptic Guidance
System and Method," filed Feb. 21, 2006, and hereby incorporated by
reference herein in its entirety.
[0061] The computing device can determine or create the desired
geometric relationship in a variety of ways. For example, the
computing device can implement finite element analysis (FEA) to
provide performance feedback on the relationships between the
components (two, three, or more). For example FEA may be used to
calculate the predicted stresses on components. Based on the
results of FEA, the computing device can be used to modify the
relationships between the components until the predicted stresses
fall within acceptable levels (i.e., the desired geometric
relationship). As another way to determine the desired geometric
relationship, the computing device can reference an existing
database of configurations to create the relationships between the
plurality of components. The desired relationship also may be
based, for example, on an image dataset, an imageless dataset, an
equation, a tolerance, a geometric model, data representative of a
patient's anatomy (e.g., preoperative CT image data, ultrasound
data), a virtual (or haptic) object associated with (or registered
to) the anatomy, a parameter relative to the anatomy (e.g., a depth
defined with respect to a portion of the anatomy); and/or the
like.
[0062] According to one embodiment, a system for implanting the
prosthetic device 5 includes the first component 10 having the
first feature 70a and the second component 20 having the second
feature 70b (as shown in FIG. 3). The computing device (or
computer) can be programmed to determine a desired geometric
relationship between the first component 10 and the second
component 20 based at least in part on the first feature 70a and
the second feature 70b.
[0063] In operation, the computing device (e.g., a CAS system) is
configured to determine a pose (i.e., position and orientation) of
one or more components of the prosthetic device 5 with respect to a
coordinate frame of reference during a surgical procedure and/or
after implantation of the components (e.g., as described above).
The coordinate frame of reference of the components can then be
registered to (mapped to or associated with) a coordinate frame of
reference of interest to achieve spatial alignment or
correspondence between the coordinate frames (e.g., using a
coordinate transformation process as is well known). The coordinate
frame of reference of interest may be any suitable coordinate
system, such as a coordinate system being used by a process running
on the CAS system, a coordinate system of the patient's anatomy,
and/or the like. For example, component pose data can be registered
to a representation (or image) of the anatomy, a geometric model
representing a desired geometric relationship between the anatomy
and the components, and/or a geometric model representing a desired
geometric relationship among the components. Using the registration
data, the system can determine, for example, (a) a spatial
relationship between the image of the anatomy and the components of
the prosthetic device 5 and (b) relative spatial relationships
among the various components of the prosthetic device 5. Using this
information, the surgeon can then adjust one or more of the
components to achieve the desired relationships.
[0064] The desired geometric relationship may be determined before
or during a surgical procedure, and the first component 10 and
second component 20 can be manipulated relative to one another
during the surgical procedure until the desired geometric
relationship is achieved.
[0065] For example, prior to preparing the bone surfaces, the
surgeon can determine where to place each of multiple components
and the consequences of those placements. As a specific example,
the first component could be the medial femoral unicondylar and the
second component could be the patello-femoral piece. The desired
relationship between the two components could be that their
articular surfaces near the transition zone be tangent. This would
ensure the patella would transition from one component to another
without major increases in stress or force. The computer would
predict the performance based on this placement, providing feedback
to the surgeon so that he/she can make appropriate adjustments.
[0066] As another example, during orthopedic surgery, a surgeon can
register an existing component in the joint (e.g., the first
component 10 having the first feature 70a or the patients bone).
The existing component may be, for example, a trial implant, a
newly installed component, or an existing implant from a previous
surgery. Based on the registration (which includes information from
the first feature 70a regarding a position and orientation of the
existing component), the surgeon can prepare the bone to receive a
new component (e.g., the second component 20 having the second
feature 70b) so that, when the new component is installed, the new
and existing components have a predetermined desired geometric
relationship. The surgeon can also verify the installation by
registering the existing and newly installed components to confirm
that the desired relationship has been achieved. As a result, the
surgeon has the ability to build the implant in the joint so that
the implant components have relative positions designed to maintain
implant life and natural patient biomechanics. This capability is
advantageous both during initial implantation of the prosthetic
device 5 and during revision surgery. For example, during a
revision surgery, rather than replacing an entire existing
prosthetic device 5, the surgeon can leave existing components that
are in good shape in place and add new components as necessary to
replace worn components and/or resurface newly diseased areas.
[0067] In operation, a surgical method according to an embodiment
of the present invention includes the following steps. In step S1,
information is acquired about a first implant (e.g., the first
component 10) disposed in a joint. In step S2, information is
acquired about a second implant (e.g., the second component 20)
disposed in the joint. As described above, the information may be
acquired, for example, by contacting at least a portion of the
implant with a trackable instrument and/or scanning at least a
portion of the implant with a detection device. In step S3, a
relationship between the first implant and the second implant is
determined based on the information acquired about the first and
second implants. In step S4, the determined relationship is
compared to a desired relationship. In step S5, if the determined
relationship deviates from the desired relationship, one or both of
the implants is adjusted to achieve the desired relationship. The
acquired information about the first and second implants may also
be used to determine a rate of wear of the first and second
implants. Additional steps include, for example, applying a force
to the joint when the information about the first implant and the
information about the second implant are acquired and determining a
condition of soft tissue in the joint based at least in part on the
information acquired about the first and second implants.
[0068] According to another embodiment, a surgical method according
to the present invention includes the following steps. In step
S101, information is acquired about a first implant (e.g., the
first component 10) disposed in a joint. In step S102, placement in
the joint of a second implant (e.g., the second component 20) is
planned based at least in part on the information acquired about
the first implant and a desired relationship between the first
implant and the second implant. In step S103, the second implant is
positioned in the joint. In step S104, information is acquired
about the second implant when the second implant is disposed in the
joint. In step S105, a relationship between the first implant and
the second implant is determined base on the information acquired
about the first implant and the information acquired about the
second implant. In step S106, the determined relationship is
compared to the desired relationship. In step S106, the first
implant and/or the second implant is adjusted to achieve the
desired relationship.
[0069] According to one embodiment, the relative positions of the
two or more components, which can comprise the prosthetic device 5
and/or the relative position of the anatomy of the patient (i.e.,
the implant joint), can be determined by acquiring the features of
the two or more components. The feature may be, for example, one of
a line, length, arc center, radius, plane, an anatomic location,
soft tissue insertion/attachment point, virtual feature or
correspondence point 240. As shown in FIG. 8, a virtual feature
(visible via a computer-generated model) may be a point 205, line
210, divot 215, axis 220, curve 225, plane 230 or surface 235 that
is not necessarily physically located on an actual component, but
may have been used, for example, to construct a component. FIG. 8
also illustrates the use of correspondence points 240 for a
patient's anatomy. Correspondence points 240 of a patient's anatomy
are unique points that are the same relative point from bone to
bone of different patients regardless of the bone shape or size.
For example, suppose the most anterior aspect of the lateral cortex
of a femur is identified as a correspondence point. Then, that
location would correspond to the same location on another femur
regardless of the femur shape or size.
[0070] The features of a prosthetic device 5 and/or a patient's
anatomy may be acquired using several acquisition methods. For
example, imaging techniques may be used to obtain an image dataset
of the features, or the computing device may acquire an imageless
dataset of the features. Laser probing, ultrasound probing,
physical instrument probing, RFID detection, CAD modeling and or
other sensor techniques may also be used to acquire features of a
prosthetic device 5 and/or patient's anatomy. Once the features are
acquired, the computing device can then determine and modify the
relationships between the identified features.
[0071] For example, FIG. 9(a) is a representation of the features,
i.e., correspondence points 240 of a femur F acquired via a CT
scan. FIG. 9(b) is a visual representation of the features, i.e.,
points 205 of a medial unicondylar or PFJ modular component
acquired with a CAD modeling acquisition method. FIG. 9(c) is a
visual representation of the computing device acquiring the
relationship between the features of the modular component shown in
FIG. 9(b) and the femur F shown in FIG. 9(a). In FIG. 9(c) the
relationship that is determined is the minimum distance between the
implant features and the femur F correspondence points. In this
embodiment, the predicted performance determined by the computing
device is the anatomic fit of the implant and femur F. In one
embodiment, the computing device uses a least squares method to
determine the best anatomic fit between the implant and femur F.
Based on the anatomic fit values, a surgeon may then modify the
size and orientation of the modular components to obtain a desired
anatomic fit.
[0072] The patient's anatomy that will receive an implant may have
several virtual features 200. For example, the most distal, most
anterior, or most posterior locations on a medial or lateral
articular surface of a bone B may be stored by the computing device
as virtual features 200. These virtual features 200 are shown, for
example as points 1-6 in FIG. 12(c). In addition, the anterior
sulcus or distal sulcus of a tochlear groove (points 7 and 8 in
FIG. 12(c)) and the most prominent medial and lateral locations
(epicondyles) (points 9 and 10 in FIG. 12(c)) may be virtual
features 200. Other virtual features 200 for joints may include but
are not limited to the mechanical axis of the femur F or tibia T,
Leo's (Whiteside's) line or AP (anterior-posterior) axis, the
epicondylar axis of the femur F, the sulcus pathway of the
trochlear groove, the highpoint pathway of the articular surfaces
and the trace line on the femur of the contact point between the
tibia and the femur throughout the range of motion.
[0073] In addition, there are numerous other features of components
and the patient's anatomy that can be acquired and modified. For
example, given a femoral unicondylar implant having a feature of
the articular surface and a patello-femoral implant having a
feature of the articular surface, the computing device may be
configured to determine the tangency of the implants' articulating
surfaces and modify the tangency based on patella stress during the
transition from the femoral unicondylar implant to the
patello-femoral implant. In the alternative, given a femoral
unicondylar implant having a feature of a set of points on the
articular surface and a femur having a feature of a set of
correspondence points, the computing device may be configured to
determine the minimum distance between the set of points on the
articular surface of the femoral unicondylar implant and the
correspondence points on the femur and modify the minimum distance
based on the anatomic fit between the femoral unicondylar implant
and the femur. Further, given a tibial trial with a feature being
the trial's most anterior point and a femoral unicondylar trial
having a feature of set points, the computing device may be
configured to determine the orientation of the femoral unicondylar
trial along the set points and modify the pose of the components
based on the predicted wear (determined from a lookup table for the
pose of the tibial trial with respect to the pose of the femoral
unicondylar trial).
[0074] Once the virtual features of the desired prosthetic device 5
and patient's anatomy are captured, according to another
embodiment, the computing device is programmed to establish or
create a relationship between the virtual features 200. This
relationship may be a component-to-component relationship or a
component-to-joint relationship. For example, as shown in FIG.
13(a), the computing device fits the bone j-curve of a modeled bone
B to that of a prosthetic device 5 component's sweep curve by a
least squares method. In the alternative, as shown in FIGS. 14-15,
the computing device can position the femoral unicondylar and
patello-femoral component so that they are tangent to one another.
Relationships may also be established by making the arc centers of
a prosthetic device 5 and bone B model coincident or by selecting a
prosthetic device 5 component that has a radii that most closely
matches the radii of a bone.
[0075] Other relationships that may be established by the computing
device include positioning the axis of a femoral unicondylar peg in
parallel with the mechanical axis of a femur, positioning the
center plane of a femoral unicondylar fin in parallel with a
mechanical axis of a femur, positioning an articular surface of an
implant component so that it is tangent to an articular surface of
a bone, positioning an articular surface of an implant so that it
is offset from an articular surface of a bone, aligning a
patello-femoral joint component sulcus path with a patella center
trace line, aligning a femoral unicondylar low point pathway (guide
curve pathway) with a tibia contact point trace line and adjusting
the distance between a femoral unicondylar anterior tip and the
termination of the patello-femoral articulating surface.
[0076] According to one embodiment, the computing device (or
computer) is programmed to determine a relationship between two or
more components of the prosthetic device 5, each having a feature,
and is further programmed to provide feedback on the performance
and/or predicted performance of the components based on the
relationship. If the performance or predicted performance values
deviate from desired values, the relationship between the
components can be modified to obtain a desired performance and/or
predicted performance. Further, the computing device is programmed
to determine the relationship between the prosthetic device 5 and
the anatomy of the patient, and provide feedback on the performance
and/or the predicted performance of the prosthetic device 5 based
on the relationship between the prosthetic device 5 and the anatomy
of the patient. If the performance or predicted performance values
deviate from desired values, the relationship between the
prosthetic device 5 and the anatomy of the patient can be modified
to obtain a desired performance and/or predicted performance.
[0077] Performance and predicted performance may be related to any
number of conditions that can characterize the operational ability
of the prosthetic device 5. For example, performance and predicted
performance may be related to wear, stress, kinematics, kinetics,
range of motion (ROM), fixation strength, ligament balance,
anatomic fit, fixation shear force and longevity of the prosthetic
device 5. Other predicted performance values include but are not
limited to polyethylene wear (mm.sup.3 per million cycles),
tibiofemoral and patellofemoral kinematics throughout the range of
motion (e.g., maximum flexion, internal/external tibial or femoral
rotation, patella flexion and tilt, femoral rollback), quadriceps
force (i.e., an indication of knee efficiency), ligament force
during a range of motion. Kinematics is related to the motion of a
body. For example, kinematics relates to AP translation, rollback,
internal and external rotation, flexion, patella tilt, patella
spin, etc. Kinetics relates to forces and/or moments acting on a
body such as compressive force, shear force, torque,
anterior/posterior (AP) force, medial/lateral (ML) force and
flexion moment.
[0078] According to one embodiment, the computing device (or
computer, e.g., a computer aided design (CAD) system using
SolidWorks, Unigraphic, Pro/E or similar programs) is programmed to
generate virtual 3D models of the prosthetic devices 5 that will be
implanted into a patient. FIGS. 10(a)-10(d) illustrate a CAD model
of a prosthetic device 5 to be implanted near the coronal articular
cross section of a bone. The computing device constructs the CAD
model by capturing profiles representing the coronal articular
cross section of a bone through a guide curve pathway. The profiles
can also be revolved about a predetermined arc center, axis or
series of axes and captured for modeling purposes. The guide curves
used to model the implant may be planar but are preferably
three-dimensional in order to capture the complex shape of the
bone. The construction geometries, i.e., the profiles, guide
curves, arc centers and axes are stored by the computing device as
virtual features 200. As described above, virtual features 200 may
be any feature, point, line, arc, radii, plane, etc., that can be
created and stored in a CAD model. In addition, as shown in FIGS.
10(a)-10(c), a prosthetic device 5 may have several other virtual
features. For example, the point at which a guide curve exits a
femoral unicondylar CAD model anteriorly (the anterior tip) or
posteriorly (max flexion) can be used as a virtual feature. In
addition, the center plane of the fin, the plane of any flat
feature, the axis of peg(s), the most distal or most posterior
point or the medial low point of the tibia may be used as virtual
features 200.
[0079] As described above, these virtual features will be used by
the computing device to determine component-to-component and
component-to-joint relationships as well as predicted performance
characteristics. To acquire the virtual features of a stored CAD
component model, the computing device makes the virtual
construction geometry of the component temporarily visible. FIGS.
10(a)-10(c) show a prosthetic device 5 and the device's virtual
features. FIG. 10(d) shows the prosthetic device 5 without its
virtual features identified. A CAD model of a patello-femoral joint
1100 created in the manner described above is shown in FIG. 11(a)
and 11(b).
[0080] According to another embodiment, and as shown in FIGS.
12(a)-12(c), the computing device is programmed to generate models
of the patient's anatomy, i.e., joints or bones B that will be
implanted with a prosthetic device 5. The computing device may be
programmed to characterize the shape of a bone or soft tissue such
as computing the ideal sagittal curve geometry and the respective
radii and arc centers. For example, the bone B in FIGS. 12(a)-12(b)
have a posterior arc radius of 22 mm, a distal arc radius of 44 mm
and an angular transition between these 2 radii of 27 degrees,
These representative geometric features may be stored by the
computing device as virtual features 200. In order to obtain the
virtual features 200 of the patient's anatomy, according to one
embodiment, a CT scan of the patient's anatomy is loaded into the
computing device. The computing device is configured to execute
anatomy characterization software that acquires the virtual
features 200 from the CT scan. According to another embodiment the
virtual features of the patient's anatomy may be obtained by, for
example tracing the contact point between the tibia T and the femur
F onto the femur F throughout the range of motion or tracing the
track of a patella onto a femur F throughout the range of motion.
As described above, these virtual features will be used by the
computing device to determine component-to-joint relationships as
well as predicted performance characteristics.
[0081] According to one embodiment, the computing device is
programmed to determine the predicted performance of a modeled
system for implanting a prosthetic device 5. As described above,
the anatomic fit of a prosthetic device 5 is an example of
predicted performance. Generally, the computing device is
programmed to use acquired virtual features 200 to conduct various
computational simulations on a prosthetic device system (e.g., a
knee implant) to obtain the predicted performance of the
system.
[0082] Predicted performance may be represented in several
different ways. For example, predicted performance may be a
numerical value that represents how well a component fits with a
joint (anatomic fit). Given FIGS. 13(a)-13(b), the computing device
may determine anatomic fit by, for example, comparing the radii of
the component to the radii of the bone. Alternatively, the
computing device may use the least squares value of the
component/bone system shown in FIGS. 13(a)-13(b) to determine the
value of the anatomic fit (predicted performance).
[0083] Generally, the computer will virtually implant a prosthetic
device 5 onto a bone B or joint in an ideal pose (e.g., when all
the articular surfaces of the femoral implant components are
tangent). Based on the ideal pose, the computing device obtains
baseline information (either by performing a functional activity
simulation, such as a deep knee bend or by obtaining the
information from a lookup table of previously performed simulations
of particular poses) such as force limitations, as well as wear and
stress limitations of the prosthetic device 5. In the alternative,
the prosthetic device 5 may be virtually implanted in less than
ideal poses so that the computing device can determine what the
affect of non-ideal prosthetic device 5 placement is on the
prosthetic device's 5 performance and the patient's health. For
example, the computing device may perform a sensitivity analysis on
a virtually implanted prosthetic device 5 by simulating a
parametric matrix of malpositioning, misalignment and varying size
compatibility permutations. According to another embodiment, in an
instance where the position of a first component is suboptimal, the
computing device is programmed to suggest the optimal relationship
and placement of one or more additional components in relationship
to the first component. The performance characteristics (i.e.,
kinematic and kinetic values, wear and stress) of the non-ideally
positioned prosthetic device 5 implant components may be compared
with the characteristics of the ideally placed implant components
to create predicted performance values that will be used as
pre-operation data by pre-operation programs of the computing
device. According to another embodiment, the computing device is
programmed to populate a lookup table with the acquired predicted
performance values. Accordingly, when the ideal pose of one or more
components is modified, if the modified position has been
previously simulated, the computing device locates the modified
pose in the lookup table to obtain the predicted performance data.
The lookup table is advantageous because it provides instant
feedback as opposed to simulating a modification. which may take
hours to complete.
[0084] According to one embodiment, the computing device is
configured to communicate/display the predicted performance values
for a given component placement to a user/surgeon. This information
may be displayed in any number of visual formats including text,
charts, tables, matrices, diagrams, etc. According to one
embodiment, the predicted performance information is presented so
that the surgeon can compare the performance values of an ideal
implant component positioning to that of a modified positioning.
For example, the predicted performance information may reveal how
the modified positioning of an implant component will cause a 30%
increase in patella shear stress, a 50% increase in patella wear
and a 40% decrease in patella fixation strength. Thus, the
predicted performance information allows a surgeon to make
iterative changes to the positioning of the implant components
until acceptable performance values are obtained.
[0085] FIG. 16 shows an example of a computational simulation
(KneeSIM) 1600 used to determine the predicted performance of a
modular knee implant 1605. The simulation shown in FIG. 16 is a 3D,
dynamic, physics-based system that simulates in vivo functional
activities for the purpose of evaluating the kinematic and kinetic
performance of knee implant designs. In the computational
simulation, component models are virtually implanted onto a
lower-leg, Oxford rig-like knee simulator 1610. The simulator 1610
has active quadriceps and hamstring actuators. Surrounding soft
tissues such as the LCL, MCL and capsule are also modeled. The knee
simulator 1610 performs activities such as a normal gait, a deep
knee bend and a lunge. During the simulation activities, the
computing device obtains data related to the kinematic and kinetic
information of the bones, components and soft tissues.
[0086] According to one embodiment, the computational simulation is
used to predict long-term wear on the implanted components and the
joints. According to one embodiment, all simulations for every
conceivable pose and component size mismatch is performed prior to
releasing the system to the public. The results of the simulations
can be stored on a computing device such that when components are
placed in a certain pose, the predicted performance values can be
displayed to a user. For example, according to one embodiment, the
computational simulation uses finite element analysis to analyze
the knee implant 1605. In this embodiment, modeled components are
virtually implanted onto a joint simulator. Here a standard
kinematic or kinetic activity pattern is used to manipulate the
knee simulator 1610, and predicted performance information is
extracted. According to another embodiment, the computational
simulation is used to predict the performance of a prosthetic
implant based on the distance between a femoral unicondylar
anterior tip and an edge of a patello-femoral articulate surface.
The distance between these two anatomic points may indicate the
amount of wear and stress that will be placed on attached implant
components. For example, if the distance between the two anatomic
points is relatively small the patella will likely be able to
transfer from one implant component to another very smoothly which
will in turn decrease the wear and tear on the implant
components.
[0087] According to another embodiment and as shown in FIG. 17 the
computational simulation can determine predicted performance values
if the articular surfaces of the femoral unicondylar 1705 and
patello-femoral joint 1710 are not tangent. Generally, in this
orientation, the patella's shear stress during transition from one
component to another is increased. The computing system presents
this information to a surgeon which in turn may modify the
positioning of the components to decrease the patella shear stress
predicted during the computational simulation.
[0088] The computational simulation is also configured to determine
if the femoral unicondylar is not aligned with the tibia contact
trace line. In this embodiment, the computational simulation will
likely show that given this configuration the fixation strength of
the components and the kinematics of the knee are compromised.
Again, the computing system presents this information to a surgeon
which in turn may modify the positioning of the components to
obtain more acceptable performance values than those predicted
during the initial computational simulation.
[0089] According to one embodiment, in a surgical method according
to the present invention, the relationship between the first
implant and the second implant is modified based on a performance
characteristic or predicted performance characteristic of the first
and second implants. For example, using the computational
simulation methods described above, prior to an actual operation, a
surgeon may simulate implanting components into a joint. Generally,
a surgeon will simulate placing the components in an ideal pose.
However, if the initial pose chosen by the surgeon does not
suitably fit the bone, the surgeon may change the pose of the
implant to provide a better anatomic fit. The computing device
running the simulation is programmed to provide predicted
performance data for the newly positioned implant. The data allows
a surgeon to position the implant component to provide a solution
specific to each patient's medical profile. For example, a surgeon
may wish to optimize the fixation strength of an implant component
for a very active patient. The computational simulation aides the
surgeon in discovering a component implant position that will
optimize the predicted fixation strength.
[0090] The ability to communicate information from the component
via the feature and the detection device provides capabilities in
addition to positioning. For example, when piezoelectric
transducers have been embedded in the component, a piezoelectric
measuring system can be used to measure piezoelectric voltage
patterns generated in response to deflections of the component
during or after surgery. As the component experiences wear over
time, the deflection pattern of the component will change, which
will cause a corresponding change in the voltage pattern generated
by the piezoelectric transducers. Differences in the voltage
pattern over time can be detected and used to quantify wear of the
component.
[0091] As another example, the feature can provide information
about the component during the life of the implant in a
non-invasive manner. For example, when the feature includes a
passive RFID tag, a surgeon can interrogate the RFID tag through
the skin and muscle of the patient using an RFID reader. In this
manner, the surgeon can determine a position and an orientation of
the component in the joint without opening the joint to expose the
implant. By capturing data with the joint in various positions
(loaded and unloaded), the computing device can obtain relative
positions of the implant components and use this data to determine,
for example, relative wear between the components and the condition
of soft tissue (e.g., ligaments) in the joint. As a result, implant
performance and life can be monitored and the need to replace an
implant component can be accurately predicted in a non-invasive
manner.
[0092] According to one embodiment, a surgical method may include
the steps of obtaining the positional information (pose) of
previously implanted modular components, using the positional
information to simulate the modular implants and determine a
performance characteristic and predicted performance characteristic
of the modular implants and modify the modular implants to optimize
the predicted performance of the modular implant. In the
alternative, one or more components of the modular implant may be
replaced to optimize the predicted performance of the modular
implant and joint.
[0093] Thus, according to embodiments of the present invention, an
orthopedic joint prosthesis and techniques that enable improved
insertion accuracy and relative placement of implant components and
non-invasive monitoring of implant wear and relative position are
provided.
[0094] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only.
* * * * *